The manufacturing of a TFT-LCD (Thin Film Transistor-Liquid Crystal Display) panel mainly comprises three stages as follows: an array process, an assembly process and a module process. The array process comprises depositing a metal film on a clean glass substrate by using a film deposition apparatus, then depositing a nonconductive layer and a semi-conductive layer, and next forming circuit patterns on the glass substrate by exposure, development, and photoresist stripping process and so on, and finally performing an etching process to form needed circuit patterns (comprising thin film transistor); the array process is accomplished after the aforesaid processes are repeated five to seven times.
Magnetron sputtering technology is widely used in sputtering technologies. The principle of the magnetron sputtering technology is explained as follows. Electrons are accelerated under the action of an external electric field and collide with atmosphere gas atoms in the vacuum chamber so as to be ionized to produce positive ions and electrons. The positive ions are accelerated to bombard the target under the action of the external electric field, and the particles (atoms or ions) of the target are sputtered out and deposited on the substrate to form a thin film. If the protectiveness of the inert gases, the sputtering yield and the industrial cost are considered, argon gas is considered as the optimal sputtering gas.
The structure of a gas ventilation device of a magnetron sputtering apparatus is shown in FIG. 1. The gas ventilation device comprises a gas inlet 71, a gas box 7 and gas ventilation pipes 72. For instance, argon gas is used as a sputtering gas in the operation process of the film deposition apparatus. The argon gas firstly enters the gas box 7 through the gas inlet 71. Then the argon gas is split by the gas ventilation pipes 72 and enters the inside of the vacuum chamber. Though the split-flow is performed by several gas ventilation pipes 72, the gas ventilation manner is difficult to avoid generating disadvantageous impact to the precision equipment in the vacuum chamber and causing certain damages. Moreover, non-uniform distribution of the argon gas in the vacuum chamber may be caused by the gas flow around outlet of the gas ventilation pipes 72, the plasma uniformity may be directly influenced, and the uniformity of the film (such as SiO2 layer or ITO layer) deposited on the substrate is finally influenced. Furthermore, in the periodical maintenance and repair process for the vacuum chamber, due to the huge pressure difference between the vacuum environment and the outside atmosphere, vibration of the equipments in the vacuum chamber and damage may be directly invoked by the impact force to the apparatus in the vacuum chamber during the process of the air rapidly rushing into the vacuum chamber.
Furthermore, the film deposition process sometimes needs to be performed in some kinds of mixed atmospheres during the film deposition by magnetron sputtering, in this situation two or more kinds of gases need to be introduced into the film deposition vacuum chamber. The gases may be directly introduced into the vacuum chamber by providing several gas ventilation pipes, the damage to the precision equipment inside the apparatus caused by the direct gas ventilation manner has been mentioned above. Some gas inlets also need to be disposed in the wall of the vacuum chamber. However, the compactness of the whole vacuum apparatus and the vacuum degree (air tightness) of the vacuum chamber are seriously affected by the excessive openings in the wall of the vacuum chamber. When mixed gases need to be introduced into the film deposition vacuum chamber, two gases A and B, for instance, as shown in FIG. 2, the gas A is introduced through the first gas inlet 41, the gas B is introduced through the second gas inlet 42, and because the bore diameters of the gas inlets should not be too big, normally 5 mm to 8 mm, it is difficult to guarantee the gas mixing effect after the mixed gases enter the inside of the vacuum chamber. Even if several split-flow pipes are disposed in the vacuum chamber as shown in FIG. 1, the gas mixing effect is also not ideal. Moreover, due to the limited inside space of the vacuum chamber, excessive split-flow devices are not allowed to be disposed on the gas ventilation device when the apparatus is manufactured. Because the bore diameter of the gas ventilation pipes is limited with respect to the space of the film deposition vacuum chamber, it is difficult to make the mixed gases uniformly distribute around the substrate on which the film is being deposited. Due to the non-uniform distribution of the mixed gases, the quality of the thin film transistor and the properties (for instance the surface evenness, conductive property, and the like, of the thin film transistor) of the product will be directly influenced. Moreover, these devices are unable to satisfy the requirements for the situation in which various gases are uniformly introduced into the film deposition environment of the vacuum chamber.